System.TimeZoneInfo.IsInvalidTime C# (CSharp) Method

		public bool IsInvalidTime (DateTime dateTime)
		{
			if (dateTime.Kind == DateTimeKind.Utc)
				return false;
			if (dateTime.Kind == DateTimeKind.Local && this != Local)
				return false;

			AdjustmentRule rule = GetApplicableRule (dateTime);
			if (rule != null) {
				DateTime tpoint = TransitionPoint (rule.DaylightTransitionStart, dateTime.Year);
				if (dateTime >= tpoint && dateTime < tpoint + rule.DaylightDelta)
					return true;
			}

			return false;
		}

        public ScheduleInstant(DateTime nowInstant, TimeZoneInfo timeZone, [NotNull] CrontabSchedule schedule)
        {
            if (schedule == null) throw new ArgumentNullException("schedule");
            if (nowInstant.Kind != DateTimeKind.Utc)
            {
                throw new ArgumentException("Only DateTime values in UTC should be passed.", "nowInstant");
            }

            _timeZone = timeZone;
            _schedule = schedule;

            NowInstant = nowInstant.AddSeconds(-nowInstant.Second);

            var nextOccurrences = _schedule.GetNextOccurrences(
                TimeZoneInfo.ConvertTime(NowInstant, TimeZoneInfo.Utc, _timeZone),
                DateTime.MaxValue);

            foreach (var nextOccurrence in nextOccurrences)
            {
                if (_timeZone.IsInvalidTime(nextOccurrence)) continue;

                NextInstant = TimeZoneInfo.ConvertTime(nextOccurrence, _timeZone, TimeZoneInfo.Utc);
                break;
            }
        }